Viruses Ppt.

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Viruses are not __. They are __. They are very small __ (__) particles.
They are __, meaning they ust do what in order to reproduce.

cells; acellular

infectious (replicating)

obligate, intracellular parasites

infect a host cell and take over that cell's metabolism

What is the capsid?

the protein coat around nucleic acid

Viral envelopes are derived from __.

host cell's membrane

Polio virus only infects __.

primate cells

Variola (smallpox) virus only infects __.

human cells

Plant viruses only infect __.

plant cells

What are the three steps in virus replication.

attachment

penetration (entry)

uncoating

Virus attachment is dependent on what?

specific receptors on the surface of the host cell

What viruses use the lytic/ lysogenic cycle?

phages

What are the steps of lytic reproduction?

attachment

entry of phage DNA (penetration) and degradation of host DNA

Synthesis of viral genomes and proteins

Self-assembly

Release (lysis)

What is different about phages that animal viruses do not do?

Unlike animal viruses that attach, penetrate, and then uncoat, phages' penetration IS their uncoating. They attach and uncoat as they penetrate. Their nucleic acid penetrates into the cytoplasm, but their capsid does not.

Prophage=?

provirus= viral DNA incorporated into cellular DNA

What are the steps to the lysogenic cycle?

Attachment

Penetration (uncoating)

Integration

Replication

True or False:
In the lysogenic cycle, the host bacterium becomes unhealthy and dies.

FALSE

In the lysogenic cycle, the host bacterium remains healthy and reproduces.